Electric weft detector for looms



Filed Sept. 9, 1946 IINVEINWTORS Jon/v.0. umvooa WALTER H. WAKEFIELD ATTORN Y Patented Feb. 22, 1949 ELECTRIC DETECTOR FOR LOOMS John C. Manoog and Walter H. Wakefield, Worcester, Mass., assignors to Crompton & Knowles Loom Works, Worcester, Mass., a corporation of Massachusetts Application September 9, 1946, Serial No. 695,626

16 Claims. 1

This invention relates to improvements in electric weft detectors for looms and it is the general object of the invention to provide a weft detecting system including an electronic tube and operating when the weft detector opens a normally closed contact.

Electric weft detectors of the type in common use require metallic ferrules on the weft carry-1 Severalhundred bobbins may be required for each loom, and since they mustall ing bobbins.

Most mechanical weft detectors used at the present time are of the so-calledside slipping type having a notched weft engaging feeler tip which is moved forwardly without'lsubstantial angular movement when sufilcient'weft ispresent during the detecting operationfbut which slips along the bobbin and has 'anangular movement when there is no weft on the bobbin to hold the tip. In those instances where detectors of this type have been used in the past to close electric contacts the connections have been such that the detector was required to have a considerable angular movement before a contact could be closed. Such an arrangement requires an objectonably large displacement of the detector by the bobbin requiring the setting of the detector so that the weft is subjected to considerable force at the time of impact between the bobbin and the detector tip.

It is another object of the invention toprovide'a side slipping weft detector which normally maintains two contacts or electrodes in engagement with each other to preserve normal conditions in the detecting system, and rely upon a very slight angular movement of the detector to It is an important ables the control means to change the grid and permit firing of the tube. A particular type of side slip weft detector is set forth hereinafter, but the broader features of the invention are not 5 necessarily limited to this specific detector.

With these and other objects in view which will appear as the description proceeds, the invention resides in the combination and arrangement of partshereinafter described and set forth.

v.Inthe accompanying drawings, wherein three forms of the invention are set forth,

. Fig, 1 is a plan view of a side slip weft detector such as may be employed with the invention, the detector being shown in normal position in 15 full lines and in indicating position in dotted lines, I

Fig. 2 is a diagramof the preferred form of electric circuit .used with the improved detecting system, and

Figs. 3 and 4 are views similar to Fig, 2 but showing the first and second modifications, re-

spectively, of the invention.

Referring particularly to Fig. 1, the weft detector D comprises a base III which in the past has been made of metal and held in place by a 7 bolt not shown passing through an opening H in the bottom of the base. A lever i2 is rockable about a pivot or stud l3 secured to the base Ill, and the lever may be made of upper and lower plates l4 and I5, respectively. A wire detector finger i6 is pivoted as at I] to the lever i2 and moves between the plates l4 and I5. A small compression spring l8 between lever i2 and the detector finger l6 normally holds the parts in the 5 full line position shown in Fig. 1. A stop pin IS on base I 0 limits movement of the finger It to the left, and that part of the detector finger it to the left of the stop pin i9 is so shaped that it cooperates with the spring it to return the detector from the dotted line to the full line position. I

A lug 20 on the forward part of the case ID has mounted thereon two spring switch contacts or electrodes 2| and 22 both held in fixed position with respect to the lug but insulated from each I other and from. the base Ill. The lever II has an operating foot 23 which is normally slightly spaced from the right end of the lower electrode 22, and a button 24 on the latter normally enses the upper electrode 2|.

' When the detector engages a bobbin provided with sufiicient weft it moves forwardly due to the fact that the notches 25 in the feeler tip 26 or finger l6 are held by the weft. At the time of .55 weft exhaustion, however, there is no weft to hold the notches 25, and the detector slides along the bobbin to some such position as that indicated in dotted lines in Fig, 1. During this sliding movement the foot 23 moves the lower electrode 22 and causes button 24 to break contact with the upper electrode 2|. This is the condition under-which the detecting system to be described hereinafter will initiate a change in loom operation, such as weft replenishment or loom stoppage.

The detector D may be similar to that shown in Payne Patent No. 2,033,003, except that the contacts are separated instead of being connected upon indication of weft exhaustion, as set forth in the patent.

Referring to the preferred form of the invention shown in Fig. 2 there are shown two power lines and 3| which energize the primary 32 of a transformer T having a secondary winding 33 to supply electric power at a relatively high voltage, and another secondary winding 34 providing electric power at a lower voltage. A gas filled power electronic tube 35 has a plate 36, control grid 31, cathode 38 and heater filament 39, and may also have a shield grid 40.

Electric detecting systems for looms generally employ some form of electromagnetic device the energization of which calls into action a train of mechanism not shown to effect either weft re-. plenishment or loom stopp ge. The electromagnetic device may be either a relay or a solenoid, and is indicated at S.

When current is able to pass through the tube 35 the following operating circuit is closed: winding 33, wire 4|, device S, wire 42, plate 36 through the tube to cathode 38, wires 43 and 44 to ground, and up from ground by way of wire 45 back to the secondary coil 33. This circuit is ordinarily dead due to the fact that the grid 31 is normally in such electric condition as to prevent flow of current through the tube, but when the grid potential has been altered to permit flow of cur- 4 when the detector gives exhaustion the contact 22 will move to the dotted rent through the tube the circuit will energize remains energized the filament will be heated and the tube will be in condition for operation, and the filament and cathode, both being grounded, will have the same potential.

In the preferred form of electric grid control means shown in Fig. 2 one side of wire 5| is connected to wire 41 and the other side is connected to wire 52 which in turn is connected to the contactor electrode 2| R has one side thereof grounded and the other side connected to junction 53 between wires 5| and 52. The grid 31 is connected by wire :5 to one side of a second resistance R the other side of which is connected by wire 56 to the contactor electrode 22.

The following grid control circuit will be energized by a very small current whenever the transformer T is alive: ground to wires 48 and 46, winding 34, wires 41 and 5|, junction 53, and resistance R back to ground. This circuit will cause grid 31 to be negative relatively to the cathode so long as electrodes 2| and 22 are in electric contact with each other. The resistance R is merely for protecting purposes to guard the it out.

A relatively high resistance series with resistance R.

line position shown in Fig. 2, thereby disconnecting the grid from its control means, and under these conditions the grid will float electrically without being able to control the tube and current can flow through the latter to energize the device S. It will be noted that the grid loses its control over the tube at the instant of'separation of the electrodes 2| and 22 which occurs very early in the angular movement of the detector finger l3. During movement of the finger to the dotted line position Fig. 1 and back to the full line position the grid will be out of control of the tube. Because of this fact the detector can be set to have a much smaller angular movement than has been possible in previous detectors of similar type, and tip 26 has such a small forward displacement that the bobbin strikes it with a blow insufilcient to injure delicate weft- A relatively large condenser C and resistance R2 can be connected around the electromagnetic device S as shown at the left of Fig. 2, if desired.

Condenser C is normally discharged but upon now of current in the operating circuit it is charged and subsequently discharges through the device 5 to continue energization thereof after contact has been reestablished between the electrodes or contacts 2| and 22.

In the first modified form of the invention the circuit for which is shown in Fig. 3 all parts, similar to the circuits of Fig. 2 bear the same' reference characters. Contact or electrode 2| is connected by wire directly to wire 41 and the polarities of the latter wire and wire 4| are such that whenever winding 34 causes electrode 2| to be negative the plate 36 of the tube will be positive, but when winding 34 causes contact 2| to be positive, a condition which would otherwise cause firing of the tube, winding 33 will cause wire 4| and therefore plate 35 to be negative. By this relationship the tube will be unable to fire during those alternations when the grid is positive, but

a the grid will be able to prevent firing of the tube when the plate is positive provided the electrodes 2| or 22 are in contact with each other. This relation of polarities also exists in the circuit shown in Fig. 2.

In a third form of the invention shown in Fig. 4 a resistance 65 is permanently connected between contacts 2| and 22 but is short-circuited when these contacts engage each other. When the contacts separate this resistance 65 will be in During normal condition of the contacts the grid will be held sufilciently negative to prevent firing of the tube, but when the contacts separate resistance 65 becomes eifective to alter the electric condition of the grid so that the latter permits the tube to fire. In Fig. 4 there is shown a battery 66 as a source of direct current having its positive side grounded and its negative side connected to contact 2| and resistance 65. This battery, however, is shown merely as a means for providing a low voltage source of electric current, and this form of the invention is not limited to the use of a battery to supply the grid bias.

The operation of the modified forms of the in;- vention is substantially the same as that described for the preferred form, separation of the contacts 2| and 22 by the detector momentarily altering the electric condition of the grid so that it has no control over the tube, This alteration may be by isolatim of the grid as in Figs. 2' and indication of wefit 3, or by effectively connecting the grid to a po tential changing resistance 65 as in Fig. 4.

The grid control electric means in Fig. 2 includes the resistance R in a .closed circuit, but this control means, as shown in Fig. 3, need'not-inelude this resistance, the. polarity derived from I wire 41 being sufflclent to bias the grid. As

shown in Fig. 4 the control circuit means may include a normally shortcircuited resistance.

From the foregoing it will be-seen that a simple form of electric detector system has been provided wherein control of the grid 31 is obtained by separation of the electrodes 2| and 22, or more generally, upon the breaking of a normally closed contact. When thedetector is in normal nonindicating condition the grid is connected to electric control means which enables it to prevent firing of the tube, b t when the detector is in indicating condition t e grid is temporarily altector finger suflices to give indication.

Having thus described our invention it will be seen that changes and modifications may be made therein by those skilled in the art without departing from the spirit and scope of the invendition disconnecting the, grid from said electric means to prevent control of the tube by the grid. '4. In an electric weft detecting system for alooi'n having an operating electric circuit including an electronic tube and an electromagnetic device which is energized to initiate a change in loom operation when current can flow through the tube, a control grid for the tube, and grid control electric means normally connected to the grid by the weft detector. and .enabling the grid to prevent new of current through the tube, said detector upon indication of weft exhaustion disconnecting the grid from said grid control electric means, whereupon the grid permits current to pass through the tube. V

5. In an electric weft detecting system for a loom having an operating electric/circuit including an electronic tube and an electromagnetic device which is energized to initiate a change in loom operation when current can flow through the tube, a control grid for the tube, a side slip weft detector which has an angular movement tion and we do not wish to be limited to the details herein disclosed, but what we claim is:

I. In an electric weft detecting system for a loom having an operating electric circuit including an electronic tube and an electromagnetic device which is energized to initiate a change in loom operation when current can flow through the tube, a control grid for the tube, two normally engaging electric contacts one of which is electrically connected to the grid, a weft detector effecting separation of said contacts when giving indication of weft exhaustion, and grid control electric means connected to the other contact and effective only when said contacts are in engagement with each other to enable the grid to prevent flow of current through the tube.

2. In an electric weft detecting system for av loom having an operating electric circuit including an electronic tube and an electromagnetic device which is energized to initiate a change in loom operation when current can flow through.

upon indication of weft exhaustion, grid control electric means normally connected to the grid and effective only when connected to the grid to trically disconnects .the grid from the grid control electric means.

6. In an electric weft detecting system for a loom having an operating electric circuit including an electronic tube and an electromagnetic device which is energized to initiate a change in loom'operation when current can flow through the tube, a control grid for the tube, a side slipping weft detector Which has an angular movement when indicating weft exhaustion, two electrodes normally in electric contact with each other, said detector when having said angular movement moving one of said electrodes out of electric contact with the other electrode, one. of said electrodes being electrically connected to the grid, and grid control electric means connected to the other electrode and effective only when said electrodes are in contact with each other to enable the grid to prevent flow of current through the tube.

'7. In an electric weft detecting loom having an operating electric circuit including an electronic tube and an electromagnetic device which is energized to initiate a change in loom operation when current can flow through the tube, a control grid for the tube, grid control circuit means including a resistance in series with a source of uni-directional electric current, an electrode connected to said grid control circuit at a part thereof connected'to the negative side of said source, a second electrode connected to the grid and normally in electric contact with the first electrode, and an electric weft detector which upon indication of weft exhaustion separates said electrodes, said grid control electric circuit when the electrodes contact each other enabling the grid to prevent flow of current through the tube, and separation of saidelectrodes altering said grid control electric circuit in such manner that the grid permits current to flow through the tube.

8. In an electricweft detecting system for a loom having an operating electric circuit including an electronic tube and an electromagnetic device which is energized to initiate a change in loom operation'when current can flow through; the tube, a control grid for the tube, a tubehavsystem for a I aceasae ing a cathode which is grounded, a source of uni-directional electric current having. the positive side thereof grounded, a pair of electrodes nected across said contacts and short circuited bythe latter when they engage each other, circuit means connecting "the source to the grid throughthe resistance and contacts when--the latter engage each other to enable the grid to prevent new of electric current through the tube. said source being connected to the grid through V the resistance only when the contacts are sepcation of weft exhaustion separates said electrodes, said source enabling the grid to prevent flow of current through the tube when the electrodes are in contact with each other, and said grid permitting current to flow through the tube when said electrodes separate. p

9. In an electric weft detecting system for a loom having an operating electric circuit including an electronic tube and an electromagnetic device which is energized to initiate a change in loom operation when current can flow through the tube, a control grid for the tube, said tube having a grounded cathode, grid control electric circuit means including a source of uni-directiona1 electric current the positive side of which is grounded, a resistance in series with said source having one side thereof grounded and having the other side thereof connected to the negative side of said source, a pair of contacts, one connected to-the grid and one connected to said grid control circuit means between said resistance and the negative side of said source to enable said source to maintain the grid at a potential which will prevent flow of current through the tube only when said contacts engage each other, and a weft detector effective upon indication of weft exhaustion to separate said contacts.

10. In an electric weft detecting system for a loom having an electromagnetic device which when energized effects a change in loom operation, an electronic tube having a control grid, operating electric circuit means including said device and tube effective to energize the device when electric current can flow through the tube, grid control electric means including two normally engaged contacts and normally enabling the grid to prevent flow of electric current through said tube but ineflective to enable the grid to prevent flow of electric current through the tube when said contacts are separated, and a weft detector which separates said contacts when indicating weft exhaustion.

11. In an electric weft detecting system for a loom having an electromagnetic device which when energized effects a change in loom operation, an electronic tube having a control grid,

operating electric circuit means including said device and tube effective to energize the device when electric current can flow through the tube, a source of electric power, two contacts, one for the grid and one for the source, connecting the source to the grid when said contacts engage each other to cause the grid to prevent flow of electric current through said tube, and a weft detector eflective when indicating weft exhaustion to separate the contacts and disconnect the source from the grid, whereupon the latter enab es electric current to flow through said tube.

12. In an electric weft detecting system for a loom having an electromagnetic device which when energized effects a change in loom operation. an electronic tube having a control grid, operating electric circuit means including said device and tube effective to energize the device when electric current can flow through the tube, a source of electric power, two contacts, one for the grid and one for the source, a resistance conarated -and the grid thereupon being ineffective to prevent flow of electric current through the tube, and a weft detector which upon indication of weft exhaustion separates said contacts.

13. In an electric weft detecting system for a loom operating with two electrodes, a weft detector which normally maintains the electrodes in contact with each other but separates said v electrodes for a brief interval when indicating weft exhaustion, a source of electric power, an electromagnetic device which when eflectively energized initiates a change in loom operation, a

normally discharged electric condenser connected in parallel with said device, and electric means effective when said detector separates said electrodes to cause said source of electric power to energize said device and also charge said condenser, the latter being'operative subsequent to said interval to discharge through said device to cause effective energization thereof.

14. In an electric weft detecting system for a loom having an operating electric circuit including an electronic tube and an electromagnetic device which is energized to initiate a change in loom operation when current can flow through the grid, a control grid for the tube, two normaily engaging electric contacts, a source of electric power, grid control electric means connecting the source to the grid and including resistance means, resistance control means effective when said contacts engage each other to enable part only of the resistance means to determine the potential of the grid and enable the latter to prevent flow of current through the.

tube, said resistance control means eflective when the contacts separate to enable all of said resistance means to determine the potential of the grid and cause the latter to permit current to flow-through the tube, and a weft detector which separates said contacts when indicating weft exhaustion.

15. In an electric weft detecting system for a loom having an operating electric circuit including an electronic tube and an electromagnetic device which is energized to initiate a changein loom operation when current can flow through the tube, a control grid for the tube, two electric contacts, a side slipping weft detector normally holding said contacts in engagement with each other but having an angular movement when indicating weft exhaustion to separate said contacts, and grid control electric means including said contacts effective when said contacts engage each other to cause the grid to prevent flow of current through the tube but eflective when said contacts are separated to alter the electric potential, of the grid in such manner as to permit current to flow through thetube.

16. In an electric weft detecting system for a loom having an electromagnetic device which when energized effects a change in loom operation, an electronic tube having a control grid. operating electric .circuit means including said device and tube eifective to energize the device when electric current can flow through the tube. grid control electric means including a source 'of unidirectional electric current the positive tacts are separated, and a weft detector which separates said contacts when indicating weft exhaustion.

JOHN c. MANOOG. WALTER H. WAKEFIELD.

No references cited. 

